Return empty string if GETRANGE of empty string
Return empty string if GETRANGE of empty string

Previously, GETRANGE of a key containing nothing ("")
would allocate a large (size_t)-1 return value causing
crashes on 32bit builds when it tried to allocate the
4 GB return string.

hanmichael/redis,alpha8/redis,Jonavin/redis,liqiang199105/redis,janeasystems/redis,liqiang199105/redis,Jonavin/redis,kolonse/redis,shanegxxiao/redis,nandhanurrevanth/redis,StartTheShift/redis-shift,StartTheShift/redis-shift,Cybermaxs/redis,sidsen/redis,miminus/redis,nandhanurrevanth/redis,kolonse/redis,enginekit/redis,quangnguyen90/redis,Cybermaxs/redis,LittlePeng/redis,alpha8/redis,quangnguyen90/redis,kolonse/redis,ScottKaiGu/redis,nandhanurrevanth/redis,nandhanurrevanth/redis,sidsen/redis,jqk6/redis,hanmichael/redis,Jonavin/redis,jqk6/redis,liqiang199105/redis,hanmichael/redis,erwin00776/redis-2.8-optimize,enginekit/redis,damy/redis,Jonavin/redis,quangnguyen90/redis,quangnguyen90/redis,upsoft/redis,damy/redis,jqk6/redis,janeasystems/redis,upsoft/redis,alpha8/redis,shanegxxiao/redis,jacklee0810/redis,jqk6/redis,fanxu/redis,Cybermaxs/redis,shanegxxiao/redis,erwin00776/redis-2.8-optimize,janeasystems/redis,upsoft/redis,fanxu/redis,upsoft/redis,laurencee/redis,jacklee0810/redis,kolonse/redis,kolonse/redis,Jonavin/redis,alpha8/redis,liqiang199105/redis,adamweixuan/redis,LittlePeng/redis,jaambee/redis,erwin00776/redis-2.8-optimize,jaambee/redis,StartTheShift/redis-shift,upsoft/redis,damy/redis,janeasystems/redis,ideaar/redis,damy/redis,jacklee0810/redis,janeasystems/redis,sidsen/redis,jaambee/redis,adamweixuan/redis,shanegxxiao/redis,alpha8/redis,adamweixuan/redis,adamweixuan/redis,miminus/redis,ScottKaiGu/redis,ideaar/redis,miminus/redis,Cybermaxs/redis,sidsen/redis,miminus/redis,jacklee0810/redis,kts12345/redis,nandhanurrevanth/redis,kts12345/redis,liqiang199105/redis,jqk6/redis,Cybermaxs/redis,fanxu/redis,enginekit/redis,ScottKaiGu/redis,kts12345/redis,sidsen/redis,sidsen/redis,enginekit/redis,laurencee/redis,enginekit/redis,laurencee/redis,miminus/redis,ideaar/redis,hanmichael/redis,erwin00776/redis-2.8-optimize,LittlePeng/redis,jacklee0810/redis,hanmichael/redis,kts12345/redis,jaambee/redis,laurencee/redis,shanegxxiao/redis,ideaar/redis,ScottKaiGu/redis,kts12345/redis,adamweixuan/redis,fanxu/redis,ideaar/redis,laurencee/redis,quangnguyen90/redis,jaambee/redis,damy/redis,ScottKaiGu/redis